This invention relates to diazo copies and particularly to eliminating the release of ammonia vapors into the air incidental to the operation of these copying machines. Diazo copiers employ ammonia vapors in contact with the exposed copying material in order to develop the print. This use of ammonia results in the emanation of some ammonia vapors into the surrounding area as a result of trace leakage from the machine itself with the highly pungent ammonia creating disagreeable working conditions for those in the vicinity of the copying machine.
In addition, the copy material usually being fibrous, such as paper or fabric, the ammonia vapors permeate the material itself such that the ammonia vapors are released in handling the prints after they have been removed from the machine. If a large number of prints are being run, the release of ammonia vapors can be considerable. If the prints are stacked, the ammonia is trapped within the paper and will be released upon subsequent handling of the prints.
Efforts to prevent the release of such ammonia vapors have led to several approaches which have been taken in the past. The most common expedient is the provision of a vacuum chamber through which the copy material passes after leaving the development chamber whereat the copy material is treated with the ammonia vapors. The vacuum chamber creates a negative pressure or suction which removes the ammonia vapors to the extent possible and passes the air through an absorption canister prior to being reexhausted into the room air. While reasonably effective in removing the vapors which leak from the development chamber, the vapors carried within the developed copy material itself will not be entirely removed, such that the ammonia vapor odor will still be detectable in handling of the blueprints, and if large numbers of copies are run, the entire area may be present with ammonia odor.
In U.S. Pat. No. 3,915,708, there is described an effective means for reducing the release of ammonia vapor by the addition of carbon dioxide vapor to the developing ammonia-water vapor mixture, and which reduces the ammonia odor problem. Again, the ammonia odor problem associated with the paper material itself is not entirely eliminated.
It has heretofore been recognized, as described in U.S. Pat. Nos. 4,109,268 and 4,092,658, that heating of the copy material in conjunction with the application of suction may more effectively remove such ammonia vapors from the paper itself. However, as described in these patents, the application of heat to paper is relatively difficult since the paper tends to become pleated or warped upon direct application of excessive heat to the paper, particularly in conjunction with mechanical stress of the paper material. The arrangement set forth in these patents includes elaborate infrared sources which are employed to indirectly cause heating of the paper, with a vacuum applied in the chamber downstream of the development chamber.
Accordingly, it is an object of the present invention to provide an effective, essentially complete degassing of the copy material after the development process such as to substantially eliminate the odor problem associated with the prints developed, as well as that leaking from the machine by being carried out of the development chamber with movement of the paper material.
It is a further object of the present invention to provide such an arrangement in which the paper material is not stressed either thermally or mechanically in such a way as to avoid the formation of waviness or pleats in the paper copy material while employing relatively simple apparatus and does not necessitate complicated controls over the application of heat.